The subject matter disclosed herein relates to semiconductor devices and, more particularly, to silicon carbide (SiC)-based semiconductor devices.
Breakdown voltage of a reverse-blocking junction is a factor that limits the reverse voltage a semiconductor device can withstand. A breakdown voltage close to its ideal limit (e.g., about 90%) is a critical performance metric for power devices, particularly high-voltage devices such as silicon carbide devices. However, avalanche breakdown can occur in such devices at a voltage substantially less than the ideal breakdown voltage because of excessively high electric fields that are present at high field points throughout the device. For example, a high field point of a blocking junction under reverse bias may occur near (e.g., at) a metallurgical junction along a region of curvature, such as at the edge of unterminated junctions.
Conventional devices may include termination regions or termination structures (e.g., JTE (junction termination extension)) to mitigate the localization of high electric fields by laterally extending the depletion region away from the edges of the active regions, thereby increasing a voltage at which the breakdown may occur. However, such termination structures are dopant sensitive and require masking or isolation during the fabrication of active area doped regions to prevent an unintentional alteration of the charge distribution in the termination structure and maintain proper blocking voltage. For example, fabrication of regions configured to perform various functions (threshold voltage adjustment regions, current spreading layers, barrier regions, or the like) within the active areas of the device require masking and etching steps and are likewise limited to low energy implants to prevent dopants from unintentionally impinging on the termination structure. Moreover, conventional doping schemes used to optimize the active area of the power device are typically incompatible with the termination regions.
Therefore the inventors have provided an improved semiconductor device and method of making thereof.